How does this medication work? What will it do for me?

Valproic acid belongs to the class of medications called anticonvulsants. It is used to manage and control of certain types of seizures. It works on the central nervous system (CNS) in the brain to reduce the number and severity of seizures.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

How should I use this medication?

The recommended dose of valproic acid is based on body weight. The dose of medication is usually started at a low level (15 mg per kg of body weight per day) to minimize side effects, and increased gradually until seizures are controlled with a minimum of side effects. The maximum recommended dose is 60 mg per kg of body weight per day.

The capsules should be swallowed whole. Do not chew or puncture the capsules. Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons. Valproic acid may be taken with food or on an empty stomach, however taking this medication with food may help to reduce stomach upset.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take valproic acid if you:

are allergic to valproic acid or any ingredients of the medication

have liver disease or significant reduction in liver function

have Alpers syndrome or Alpers-Huttenlocher syndrome, conditions caused by nervous system breakdown

have porphyria

have certain metabolic disorders (urea cycle disorders)

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

diarrhea

dizziness

headache

indigestion

nausea

sedation

vomiting

weakness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

abdominal or stomach cramps (severe)

changes in hair (hair loss or increased hair on face, chest, and back)

symptoms of a serious allergic reaction, including angioedema (e.g., hives; swelling of the face, mouth, hands, or feet; and difficulty breathing)

signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort

thoughts of self-harm

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood clotting: This medication may make it more difficult for the blood to clot. If you take anticoagulant (blood thinning) medications, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you notice any signs of bleeding, such as frequent nosebleeds, unexplained bruising, or black and tarry stools, notify your doctor as soon as possible. Your doctor will order routine blood tests to make sure potential problems are caught early.

Take appropriate precautions and ensure that all doctors involved in your care are aware of all medication use. Tests for blood clotting should take place before any surgery. Platelet count and coagulant tests should take place before starting treatment with valproic acid.

Drowsiness/reduced alertness: Valproic acid may affect the mental or physical abilities needed to drive or operate machinery. Avoid driving, operating machinery, or performing other hazardous tasks until you have determined how this medication affects you.

Hypersensitivity syndrome: A severe allergic reaction called hypersensitivity syndrome has occurred for some people with the use of valproic acid. Stop taking the medication and get immediate medical attention if you have symptoms of a severe allergic reaction, including fever, swollen glands, yellowing of the skin or eyes, or flu-like symptoms with skin rash or blistering.

Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver failure has occurred infrequently for people taking valproic acid, usually during the first 6 months of treatment. Children under 2 years of age who take valproic acid together with other epilepsy medications are at greatest risk (nearly 20 times greater) of developing serious liver problems. These children typically have other medical conditions such as congenital metabolic disorders, mental retardation, or organic brain disease. Liver function tests should take place before starting treatment with valproic acid.

Serious liver problems may be preceded by symptoms such as loss of seizure control, malaise, weakness, lethargy, loss of appetite, and vomiting. People who take valproic acid should tell their doctor at once if they experience these symptoms. Increases in the levels of ammonia in the blood, with or without lethargy or coma, have been reported and may be present despite normal liver function tests.

Pancreatitis: Cases of life-threatening pancreatitis (inflammation of the pancreas) have been reported for both children and adults. This can occur at any time during the use of valproic acid. If you experience signs of pancreatitis such as abdominal pain on the upper left side, back pain, loss of appetite, nausea, fever, chills, rapid heartbeat, or swollen abdomen contact your doctor immediately.

Sedation: Valproic acid may cause sedation, especially when combined with another sedating drug such as alcohol.

Seizures: Some people experience an increase in seizures or new types of seizures when taking valproic acid. If you experience a change in your seizures, contact your doctor as soon as possible.

Suicidal thoughts: There is a small risk that this medication may result in thoughts of suicide. If you experience these symptoms or any other behaviour change while taking this medication, contact your doctor immediately. Family members or caregivers of people who are taking this medication should contact the person's doctor immediately if they notice unusual behaviour changes.

Pregnancy: There is an increased risk of serious birth defects for a child whose mother takes valproic acid during pregnancy. Valproic acid may cause a defect of the spine called spina bifida, cleft palate, heart defects, autism, or slowed or reduced mental development. Women of child-bearing age must use effective birth control while taking valproic acid.

Before becoming pregnant, women with epilepsy should speak to their doctor about other options for seizure medications. If you become pregnant while taking this medication, contact your doctor immediately.

People who need medications to prevent major seizures should not stop taking them. If it is necessary to stop taking this medication, your doctor will advise you of the best way to reduce or change the medication.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking valproic acid it may affect your baby. Talk to your doctor about whether you should continue breast-feeding. As a general rule, women who are taking valproic acid are advised not to breast-feed.

Children: If valproic acid is given to children 2 years old or younger, it should be used with extreme caution and as a single medication. The benefits of seizure control should be weighed against the risk.

Seniors: People over the age of 65 may be more at risk of developing side effects from this medication and may require lower dosages.

What other drugs could interact with this medication?

There may be an interaction between valproic acid and any of the following:

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

stop taking one of the medications,

change one of the medications to another,

change how you are taking one or both of the medications, or

leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.